i have forgot my password for admin

i have frogot my passwrd for admin login and have tried to reset it by booting up with dvd but it does not boot with dvd and i couldnt reset the password.please any tips i do not want to lose my files.

i have a acer laptop and this problem has been going on, ever since i got this computer its always been blocked by admin. ive tried alot of things to reset or fix this but with no succses. how do i fix this?

I forgot my password to get in I am able to turn on the computer but when I get to the password I have try the ones that I know and it says incorrect password I try using an usb to reset it sends me to the password reset wizard I hit next and it shows me the password key disk and it says removable disk I click on next and it says this disk is not a password reset disk I don't know what to do I didn't back up the computer when I got it is new and I forgot to do it please help me